#include <stdint.h>
#include <stddef.h>

// Force the compiler to assume we have support for the CRC32 intrinsic. We will check for our selves later.
// Clang will define both __llvm__ and __GNUC__ but GCC will only define __GNUC__. So we need to check for __llvm__
// first.
#if ((defined(__llvm__) && (defined(__x86_64__) || defined(__i386__))))
#pragma clang attribute push(__attribute__((target("crc32"))), apply_to = function)
#elif ((defined(__GNUC__) && (defined(__x86_64__) || defined(__i386__))))
// GCC Only lets you enable all of sse4.2 so we will for just this file and reset it at the end.
#pragma GCC push_options
#pragma GCC target("sse4.2")
#endif

// Include headers for the CRC32 intrinsic and cpuid instruction on windows. No need to do any other checks because it
// assumes the target will support CRC32
#ifdef _WIN32
#include <immintrin.h>
#include <intrin.h>
// Same as above but these platforms use slightly different headers
#elif ((defined(__GNUC__) && (defined(__x86_64__) || defined(__i386__))))
#include <nmmintrin.h>
#include <cpuid.h>
#elif defined(__aarch64__) && defined(__ARM_FEATURE_CRC32)
// Nothing cause its a compiler builtin
#else
#define NO_CRC_INTRIN
#endif

#if defined(__aarch64__) && defined(__ARM_FEATURE_CRC32)
#define INTRIN_CRC32_64(crc, value) __asm__("crc32cx %w[c], %w[c], %x[v]" : [c] "+r"(crc) : [v] "r"(value))
#define INTRIN_CRC32_32(crc, value) __asm__("crc32cw %w[c], %w[c], %w[v]" : [c] "+r"(crc) : [v] "r"(value))
#define INTRIN_CRC32_16(crc, value) __asm__("crc32ch %w[c], %w[c], %w[v]" : [c] "+r"(crc) : [v] "r"(value))
#define INTRIN_CRC32_8(crc, value) __asm__("crc32cb %w[c], %w[c], %w[v]" : [c] "+r"(crc) : [v] "r"(value))
#elif defined(__GNUC__) || defined(_MSC_VER)
#define INTRIN_CRC32_64(crc, data) crc = _mm_crc32_u64(crc, data)
#define INTRIN_CRC32_32(crc, data) crc = _mm_crc32_u32(crc, data)
#define INTRIN_CRC32_16(crc, data) crc = _mm_crc32_u16(crc, data)
#define INTRIN_CRC32_8(crc, data) crc = _mm_crc32_u8(crc, data)
#endif

static const uint32_t crc32Table[256] = {
    0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L, 0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL, 0x8AD958CFL,
    0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL, 0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L, 0x105EC76FL, 0xE235446CL,
    0xF165B798L, 0x030E349BL, 0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L, 0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L,
    0x89D76C54L, 0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL, 0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL,
    0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L, 0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L, 0x6DFE410EL,
    0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL, 0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L, 0xF779DEAEL, 0x05125DADL,
    0x1642AE59L, 0xE4292D5AL, 0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL, 0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L,
    0x6EF07595L, 0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L, 0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L,
    0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L, 0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L, 0x5125DAD3L,
    0xA34E59D0L, 0xB01EAA24L, 0x42752927L, 0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L, 0xDBFC821CL, 0x2997011FL,
    0x3AC7F2EBL, 0xC8AC71E8L, 0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L, 0x61C69362L, 0x93AD1061L, 0x80FDE395L,
    0x72966096L, 0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L, 0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L,
    0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L, 0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L, 0xB602C312L,
    0x44694011L, 0x5739B3E5L, 0xA55230E6L, 0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L, 0x3CDB9BDDL, 0xCEB018DEL,
    0xDDE0EB2AL, 0x2F8B6829L, 0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL, 0x456CAC67L, 0xB7072F64L, 0xA457DC90L,
    0x563C5F93L, 0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L, 0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL,
    0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L, 0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL, 0x1871A4D8L,
    0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL, 0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L, 0xA24BB5A6L, 0x502036A5L,
    0x4370C551L, 0xB11B4652L, 0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL, 0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL,
    0x3BC21E9DL, 0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L, 0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL,
    0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L, 0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L, 0xFF56BD19L,
    0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL, 0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L, 0x0417B1DBL, 0xF67C32D8L,
    0xE52CC12CL, 0x1747422FL, 0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL, 0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L,
    0x9D9E1AE0L, 0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL, 0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L,
    0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L, 0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL, 0xE330A81AL,
    0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL, 0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L, 0x69E9F0D5L, 0x9B8273D6L,
    0x88D28022L, 0x7AB90321L, 0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL, 0xF36E6F75L, 0x0105EC76L, 0x12551F82L,
    0xE03E9C81L, 0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL, 0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL,
    0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L
};
// On platforms that we know will never support a crc32 instruction (such as the WiiU) we will skip compiling this
// function in.
#ifndef NO_CRC_INTRIN

static uint32_t CRC32IntrinImpl(unsigned char* data, size_t dataSize) {
    uint32_t ret = 0xFFFFFFFF;
    int64_t sizeSigned = dataSize;
// Only 64bit platforms support doing a CRC32 operation on a 64bit value
#if defined(_M_X64) || defined(__x86_64__) || defined(__aarch64__)
    while ((sizeSigned -= sizeof(uint64_t)) >= 0) {
        INTRIN_CRC32_64(ret, *(uint64_t*)data);
        data += sizeof(uint64_t);
    }

    if (sizeSigned & sizeof(uint32_t)) {
        INTRIN_CRC32_32(ret, *(uint32_t*)data);

        data += sizeof(uint32_t);
    }
// On 32 bit we can only do 32bit operations
#elif defined(_M_IX86) || defined(__i386__)
    while ((sizeSigned -= sizeof(uint32_t)) >= 0) {
        INTRIN_CRC32_32(ret, *(uint32_t*)data);
        data += sizeof(uint32_t);
    }
#endif
    if (sizeSigned & sizeof(uint16_t)) {
        INTRIN_CRC32_16(ret, *(uint16_t*)data);
        data += sizeof(uint16_t);
    }

    if (sizeSigned & sizeof(uint8_t)) {
        INTRIN_CRC32_8(ret, *data);
    }

    return ~ret;
}
#endif

static uint32_t CRC32TableImpl(unsigned char* data, size_t dataSize) {
    const uint8_t* p = data;
    uint32_t crc = 0xFFFFFFFF;

    while (dataSize--)
        crc = crc32Table[(crc ^ *p++) & 0xff] ^ (crc >> 8);

    return ~crc;
}

uint32_t CRC32C(unsigned char* data, size_t dataSize) {
#ifndef NO_CRC_INTRIN
    // Test to make sure the CPU supports the CRC32 intrinsic
    unsigned int cpuidData[4];
#ifdef _WIN32
    __cpuid(cpuidData, 1);
#elif __APPLE__ || (defined(__aarch64__) && defined(__ARM_FEATURE_CRC32))
    // Every Mac that supports SoH should support this instruction. Also check for ARM64 at the same time
    return CRC32IntrinImpl(data, dataSize);
#else
    __get_cpuid(1, &cpuidData[0], &cpuidData[1], &cpuidData[2], &cpuidData[3]);
#endif

    if (cpuidData[2] & (1 << 20)) { // bit_SSE4_2
        return CRC32IntrinImpl(data, dataSize);
    }
#endif // NO_CRC_INTRIN
    return CRC32TableImpl(data, dataSize);
}

#if ((defined(__llvm__) && (defined(__x86_64__) || defined(__i386__))))
#pragma clang attribute pop
#elif ((defined(__GNUC__) && (defined(__x86_64__) || defined(__i386__))))
#pragma GCC pop_options
#else
#endif
